This simple circuit can be used to monitor whether a battery is charging or not. The voltage comparator IC LM393 is the heart of this circuit. The LED D1 will remain ON whenever there is at least 25 milli ampere current flowing to the battery. This particular circuit is designed for a 12V battery with charging current less than 1A.By slightly modifying the component values, the charging current and voltage can be modified.

Circuit diagram with Parts list.

Notes.

Assemble the circuit on a good quality PCB.

The IC1 must be mounted on a holder.

Do not use this circuit with batteries has more than 1A charging current.

Dear sir, is it right to use 1N5822 diode instead of the one you have mentioned in your circuit (i.e1N5819). I am using 6v 4.5ah SLA battery, will this circuit stop charging at 6.9v or 7.00v. i have used 220k for R1 and when the LED will go off, in this case it should go off at voltage level of 6.9v or 7v. But i am doubtfull sir that it will not go off. please explain …..

Dear Bashir the indication will go off, when the charging current falls below 25mA. 1N5819 rated for 1 amp, will do but you can use the 3 Amp rating 1N5822 also. This circuit does not sense the voltage level of the battery. for a proper cut off use a voltage regulated power supply between 6.9 to 7 volt with a charging capability of 1 amp.

sorry, i still ununderstand with the formula. can you tell me the R on lm3914 schem which have to change and with which one? it for 4v/1000mA batt. sorry, i have too much quest, i just a rookie. thanks

Hi Sugiman this can be used with any battery up to 30 volts. you can set the current such that it show up to trickle level or it can indicate just whenever the battery is connected for charging (called mandatory charge indicator) please go through my 19th July comment for calculation to use with other battery voltages.

ok tq mr. seetharaman. i’ll try to find the ic here. i on indonesia country. but, i have 2 more question. is the circuit will display the power status and charging stat until it full? and is it work for 4 v batt? thaks,

any body, can u tell me about batery indicator, which the display like a batery indicator on screen on cellphone(like nokia). its 4 or 6 bar strips and while charging, leds shown the level until full all lighting. tq

Hi Praveena PD across R2 is 12 X (2.2/1000) that is 26.4mV. to get the same mV across 1 ohm you have to flow 26.4mA. if you reduce the battery voltage to 6volt 4.5AH the current for trickle is approx 45mA. hence 60mA is preferred value hence 60 X1 = 60mV. 60mV across 2.2K hence for 6 volt it is 220k. (switching off of LED indicates battery is fully charged. if you want still indication even the charge is than trickle use say 25mA. then 25mV across 2.2K for 6volt. 528K nearby preferred value is 510K.